Water sometimes collects on windows and other glazing assemblies, like any other surfaces, in the form of condensation. Condensation forms, for example, when a window surface is cooled to the point where the rate of evaporation from the surface is lower than the rate of condensation to the surface from the air. A cooler surface or a higher moisture content in the air will make condensation more likely. Consider a winter environment where the outdoor conditions are relatively cold and the indoor environment is relatively warm, and at least somewhat humid. When condensation forms on a glazing in such environments, it is typically more likely to occur at the perimeter of the room-side glass surface, i.e., near the frame. This is because the edge region of a multiple-pane insulating glass unit (“IG unit”) typically is less thermally insulative than its center region. As will be appreciated, the center region of an IG unit has at least one thermally insulative between-pane space separating two glass panes. This space may contain air, a mix of air and thermally insulative gas (e.g., argon), or a vacuum. As a result, heat transfer through the center region of an IG unit is particularly low. While heat transfer at the edge region of an IG unit may also be low, it is typically somewhat higher than at the central region due to the presence of a spacer and sealant connecting the panes. The spacer and sealant, while engineered to reduce heat transfer, provide a thermal conduction pathway that is not present at the center region of an IG unit.
Thus, in winter environments, the perimeter of the room-side glass surface of an IG unit will typically be cooler than the center and is more likely to form condensation than is the center region. While particular winter conditions have been mentioned, it will be appreciated that the perimeter regions of a glazing can form condensation in various seasons, climates, environments, and glazing arrangements. Thus, it would be desirable to provide a coating system that reduces the potential for glazing perimeter condensation to occur.